It is known to use adjustable exhaust gas flaps in exhaust gas systems of internal combustion engines and when using said flaps it is possible to selectively close or open a cross section of an exhaust gas pipe. These exhaust gas flaps are moved by an adjustment drive. It is possible to positively influence the consumption of fuel and/or the harmful emissions of an internal combustion engine by selectively opening and closing the exhaust gas flaps. Furthermore, it is possible with such exhaust gas flaps to control the noise behavior of an internal combustion engine.
Moreover, exhaust gas flaps are used in connection with cylinder deactivations. In this case, the exhaust gas pipes that are associated with the cylinders that are to be deactivated are closed by means of exhaust gas flaps.
Exemplary exhaust gas flaps and their drive systems are disclosed in DE 10 2009 016 597 A1, WO 2015/078432 A1, DE 10 2009 013 815 A1 and also DE 10 2011 107 088 A1.
Owing to the intense thermal and heavy mechanical load on exhaust gas flaps and their drive systems, the coupling of the drive system to the exhaust gas flap is of great importance. Coupling elements that connect the adjustment drive and the exhaust gas flap are generally loaded in two ways. On the one hand, it is necessary for the coupling elements to transfer torque from the adjustment drive to the exhaust gas flap in order to open and to close the exhaust gas flap. On the other hand, an axial force is applied by way of the coupling element to the mounting arrangement of the exhaust gas flap. The axial force is necessary in order to seal the spindle feedthrough of the exhaust gas flap. Furthermore, vibrations that make themselves noticeable acoustically as rattles are avoided via the axial force.
The aim is to embody the transfer path of the torque as rigidly as possible in order to be able to move the exhaust gas flap as precisely as possible and in such a manner that causes few vibrations. However, in the case of the axial coupling, a high rigidity causes a high friction on the spindle feedthrough of the exhaust gas flap, and thereby a mechanical load of the associated sealing arrangement and also an increased resistance when moving the exhaust gas flap. The aim is therefore to embody the axial coupling as less rigid, in other words as more elastic. There is, in other words, a conflict of objectives with regard to the requirements of the rigidities of the coupling between the adjustment drive and the exhaust gas flap. This leads to the fact that in the prior art it is always necessary to find a compromise between the axial rigidity of the coupling and the rigidity of the transfer path of torque. There is a need for an improvement.